Transmission Congestion Management In Electricity Market Environment

With the power grid opening and the electric trade that across the district increasing gradually, especially actualization of many big projects in our country including the conjunction of electric power grid between the big districts, and the transportation of the electric power from west to east, transmission congestion will be serious increasingly. Transmission congestion arise from the limitation of the themal capacity of the power line and the stability limitation of the electric power system.The safety and stability of the power system will be threatened by the congestion.The electricity trades should not be accomplished. Transmission congestion will affect the optimal scheme and the utilization of resources.The market power may be abused by merchants. The electricity price would be distorted. In order to eliminate transmission congestion a series of rules should be established. The generators and loads should be controlled availably, and these rules would be used to insure the safety and reliability of the power system.The physical characteristic of the power grid should be considered at first when managing transmission congestion, including switching the congestion circuit, adjusting transformers and controlling the field excitation of condensers, and making use of FACTS. If congestion is still exist after using up these methods, the market mechanism should be made use of to manage congestion. Under the electricity market, the investigative point is how to carry out the increment of electric power trades or decrease for reducing the power flow of the over loading circuits.Because of the differences in market model, political setup and technique develops etc, the scheme of congestion management is classified mostly three kind, namely the decrease of contract trades, the reservation of transmission capacity in advance, and the readjustment of power system.A bidding model is studied under electricity market at first. Then the congestion management method according to sort and distinction is described on the base of sensitivity analysis, at last, the pricing problems of congestion cost is studied, the calculation method of congestion cost is described by the cost flow method, and the congestion cost is alloted. Each method is validated by practical examples, the feasibility and validity are testified.